Product Review - Marsh Sound Design A-400s Stereo Power Amplifier - August, 2000


John Kotches


Marsh Sound Design A-400s Two-Channel Power Amplifier

Power: 200 Watts RMS Per Channel at 8 Ohms, 330 Watts RMS Per Channel at 4 Ohms

MFR: 20 Hz - 80 kHz - 1 dB

THD: 0.02% 20 Hz - 20 kHz

S/N: 110 dB A Weighted

Input Impedance: 58 kOhms Unbalanced, 4 kOhms Balanced

Size: 7 1/8" H x 19" W x 18 1/4" D

Weight: 45 Pounds

MSRP: $1,995 USA



Marsh Sound Design, 62 El Camino Drive, Corte Madera, California 94925; Web


Richard Marsh is a veteran in the audio industry, and you may very well have some of his other efforts in your system already.  Dr. Marsh is a world renowned expert on capacitors.  Some of his designs have received critical acclaim (MIT Z Series and Monster Cable HTS power products), and his Multicap capacitors have gained widespread use by manufacturers worldwide.  If you'd like to see which manufacturers are using his current line of capacitors, check out

Marsh Sound Design (MSD) marks Dr. Marsh's first time around for marketing audio components under his own name.  The current product lineup includes a Solid State/Tube Hybrid Preamp, plus several power amplifiers.  Plans are in the works for a Home Theater Preamp/Processor and multi-channel amplifiers.


Click this photo to see larger version

(Click on photos to see larger versions)

This amp is solidly built, with silver faceplate and the (almost) ubiquitous blue power LED.  It's moderately heavy at 45 pounds and is square in footprint.  There are no handles, nor is there provision for rack mounting as shipped from the factory.  The end pieces of the amplifier do have sufficient clearance from the heat sinks for your hands to pick up and carry the amp if necessary.

The rear panel also shows solid construction, including dual binding posts for quick and easy bi-wiring of your speakers if they're bi-wire capable.  Selection of single-ended (RCA) or balanced (XLR) operation is performed by a switch on each channel, and the posts are fairly substantial.  Power cord tweakers take note, this amp has a detachable power cord - feel free to substitute the cord of choice in your system. 

Click this photo to see larger version   

When you open the chassis, the detail and care in assembly remain evident.  Note the symmetry between the left and right halves of the amplifier as viewed from above (you can click on the photos for larger view).  Shared components are limited to the power input (at the rear of the chassis), the toroidal transformer, and the front panel power circuitry.  Six Motorola bi-polar FETs are used per channel, as well as Nichicon capacitors.  Also included is a power filter integrated into the power supply so that even those without line conditioning should enjoy excellent performance from this amplifier.

Listening to the amplifier

Whenever a new piece of gear goes into my system, there's an initial rush of excitement that comes from the novelty of sonic differences and the pleasure of having a new toy.  When listening to any new product, if there is something that sticks out as noticeably unpleasant, then I might not be happy with it in the long run.  To me, it indicates something is out of balance. With the A-400s, nothing really struck me out of the box as being out of place.

There were a few things that showed up the more I listened.  First and foremost, this amplifier is capable of retrieving incredible detail from recordings.  For a lot of the jazz recordings that I enjoy, it's the subtleties of sticking differences a drummer will use on cymbals, trumpet valve noises, or saxophone key clatter that aren't noticeable on lower resolution systems.  My reference for this is the Dave Brubeck recording, Tritonis which has Jerry Bergonzi on Tenor Sax (a personal favorite of mine).  Track 2, Like Someone in Love, ends with an extended obligatto by Bergonzi.  He's all over his horn,  at times almost whispering, while at other times he's loud and forceful.  During the quiet passages, with the A-400s, the clatter from his keys is a bit more pronounced than I've heard before.  During furious passages, with sheets of notes flying off of his sax, the amp still manages to point out that these sheets are made up of many individual notes in rapid fire succession .  The sound of his horn has the appropriate combination of stridency and body that is his signature sound.

Next up was a relatively new recording to me, and the only recording that actually made this amp overload at high volumes Percy Grainger Works for Wind Orchestra 2.   My speakers aren't noted for their efficiency, and about 4:00 or so into Irish Tune from County Derry,  when the pipe organ kicks in, with the orchestra playing fortissimo, I managed to get the amplifier's protection circuitry to engage.  The amplifier automatically muted input, and waited a few seconds, as I frantically hit the volume down.  I don't know how loud the room was at this point, but I detected only a modest sense of strain just prior to shutdown.  Ten to fifteen seconds later, the amplifier came  back on and continued playing with none the worse for the wear.  I listened to several tracks for reviewing, and it was nice to hear the amplifier retaining the characteristics of individual instruments without losing the cohesiveness of the group. Percussion (xylophone in particular) rang out with sharpness and clarity characteristic of a live performance.   Lesson learned, if you have inefficient speakers, don't expect concert hall levels from this amp. Look at the monoblocks (Model A400M or A600M)  - according to MSD, they'll be out in the fourth quarter of 2000.

I'm not a huge soundstage junkie, but I tend to focus on musical details.  My gauge for soundstage width is another acoustic jazz album, led by trumpeter Tom Harrell.  The recording is Upswing, and I used the title cut.  On an amp with good soundstage width, you can hear Phil Woods' alto from beyond the left speaker and Joe Lovano's tenor beyond the right speaker.  This amp compressed the soundstage so that the saxes are much closer to the trumpet than my reference.  I also noticed that the amp is providing me with "just the facts" without embellishment, coloration, or detraction.

My biggest concerns have nothing to do with the sonics of the amplifier, but rather with the warranty.  In comparison to others in its price range, the two year warranty is a bit short.  Given the parts and construction quality, I'm surprised that it isn't longer.  Perhaps Marsh Sound Design will address this in the future, as his company grows.

The first review sample developed a power supply problem about 3 days after receipt.  After contacting the folks at MSD, the review sample was returned, and a replacement was sent after a bit of a delay.  My second sample was fine, and all referenced listening was done with this second amplifier.


Richard Marsh has designed a solid amplifier, capable of holding its own against other amplifiers in its price range.  This amplifier recovers tremendous detail, with a straightforward, uncolored presentation.  Combined with the quiet background, you've got a fine effort from Marsh Sound Design.  It is well worth a serious listen if your stereo amplifier budget is near or slightly above this price range.  Like many of its competitors, this amp isn't capable of doubling down its output power into a 4 Ohm load.  For real world listening, I didn't find this to be a problem in my system.

Associated equipment used for the review:

Golden Theater GTX-1  Preamp/Processor
Toshiba SD-3108 DVD player (Digital Transport)
Acoustat Spectra 22 Loudspeakers
Bryston 4B power amplifier
Harmonic Tech Pro-Silway Mk II Interconnects
Harmonic Tech Cyberlink Silver Digital Cable
Better Cables Premium Speaker Cable

Recordings referenced:

Dave Brubeck Quartet Tritonis Concord CCD-4129
Percy Grainger  Works for Wind Orchestra 2  Chandos CHAN-9630
Tom Harrell Upswing Chesky JD103

- John Kotches -

© Copyright 2000 Secrets of Home Theater & High Fidelity
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